The proposed research seeks to further our understanding of drugs of abuse. Major emphasis in the proposed investigation is upon drug-induced stimulus control in rats by narcotic analgesics but the methods are applicable to other classes of drugs of abuse and the data to be obtained are of potential relevance to man. Stimulus control will be induced using morphine, ketocyclazocine, and SKF-10047, respectively, and representative opiates and non-opiates will be cross tested. It is anticipated that the methods developed in this fashion will provide a means of preclinical identification of opiate-like drugs likely to be subject to abuse by man. In addition, the methods of drug-induced stimulus control will be used to access the relative sensitivity of naive, morphine-dependent, and post-dependent rats to the effects of morphine, d-amphetamine, quipazine, an nicotine. The results will provide information regarding the hypothesis that physical depndence to opiates induces persistent alterations in brain sensitivity.